Many power converters include switches and one or more capacitors that are used, for example, to power portable electronic devices and consumer electronics. Switch-mode power converters regulate the output voltage or current by switching energy storage elements (i.e. inductors and capacitors) into different electrical configurations using a switch network. Switched capacitor converters are switch-mode power converters that primarily use capacitors to transfer energy. In such converters, the number of capacitors and switches increases as the transformation ratio increases. Switches in the switch network are usually active devices that are implemented with transistors. The switch network may be integrated on a single or on multiple monolithic semiconductor substrates, or formed using discrete devices.
Typical DC-DC converters perform voltage transformation and output regulation. This is usually done in a single-stage converter such as a buck converter. However it is possible to split these two functions into two specialized stages, namely a transformation stage, such as a switching network, and a separate regulation stage, such as a regulating circuit. The transformation stage transforms one voltage into another, while the regulation stage ensures that the voltage and/or current output of the transformation stage maintains desired characteristics.
For example, referring to FIG. 1, in one converter 10, a switching network 12A is connected to a voltage source 14 at an input end thereof. An input of a regulating circuit 16A is then connected to an output of the switching network 12A. A load 18A is then connected to an output of the regulating circuit 16A. Power flows between the voltage source 14 and the load 18A in the direction indicated by the arrows. Such a converter is described in US Patent Publication 2009/0278520, filed on May 8, 2009, the contents of which are herein incorporated by reference.